45-V, 2.3-A LED driver for high current LED applications offers maximum junction temperature of 150 degrees C

August 23, 2012 //
By Paul Buckley

Linear Technology has unveiled the H-grade version of the LT3518 LED Driver which is a 45 V, high-side current sense DC/DC converter designed to drive high current LEDs at constant current.

The device’s 3 V to 30V input voltage range with transient protection to 40 V makes the LT3518 ideal for a wide variety of applications, including automotive, industrial and architectural lighting.

The H-grade version operates with a junction temperature up to 150°C, compared to the E- and I-grade versions’ 125°C maximum junction temperature. All electrical specifications are identical for the E, I and H. The H-grade parts are tested and guaranteed to the maximum junction temperature of 150°C. They are ideal for automotive and industrial applications, which are subjected to high ambient temperatures.

The LT3518 can drive up to eight 300 mA white LEDs from a nominal 12 V input, making it well suited for applications such as automotive display backlighting. The LT3518 senses output current at the high side of the LED, enabling buck, buck-boost or boost configurations. It can deliver efficiencies up to 90% in boost mode from a 4 mm x 4 mm QFN package. The LT3518 offers True Color PWM dimming, delivering constant LED color with dimming ranges of up to 3,000:1. For less demanding dimming requirements, the CNTRL pin can be used to offer 10:1 analog dimming. Its fixed frequency, current-mode architecture ensures stable operation over a wide range of supply and output voltages. A frequency adjust pin enables the user to program the frequency between 250 kHz and 2.5 MHz to optimize efficiency while minimizing external component size.

Availability and Pricing

The LT3518HUF is available from stock in 16-pin QFN package, priced starting at $3.79 each in 1,000-piece quantities.